Biology in the News Explained

Politics and Biology, Part 2

My last post covered a paper that found brain physiological correlates of political attitudes. That paper did not address the origin of the physiological differences, i.e. whether they might be genetic or environmental. An earlier paper (Alford, J.R., C.L. Funk, and J.R. Hibbing, 2005. Are political orientations genetically transmitted? American Political Science Review, 99:153-167), though, does claim a genetic origin for particular suites of political attitudes. While authors acknowledge that on the surface this seems nonintuitive, they back up their case by citing numerous studies that other social attitudes have a genetic origin.

This is another example of a twin study being used to support genetic causes of differences among people previously assumed to be purely environmental. The survey data used were collected not as part of this study, but recycled from a previous study, and include the usual thousands of twin pairs, because these authors, like so many others, assume that more is better, when that is not in fact true. A weakness of the data set is exposed when they calculate a surprisingly high 40% heritability of educational attainment, without any mention of the demographics of the survey-takers. Could there be any correlation of socioeconomic and education level and the willingness to return an esoteric research survey? It seems likely, but there is no consideration here of the possible effect.

The authors are all political scientists whose paper, published in a political science journal, purports to teach other political scientists how genetics works. (One can’t help but wonder how they would react to a bunch of biologists pontificating on a political topic in a biological journal.) It probably does not matter whether or not any biologists actually reviewed this paper; twin studies appear in plenty of biological journals as well.

All the arguments the authors make supporting their assumptions, come from other twin studies, which have the same methodological issues, stemming from the ethical impossibility of manipulating human phenotype and social environment. The most important assumption upon which the results are based is of course the one apparently made in all twin studies: correlation in survey scores between identical twins minus correlation in scores between fraternal twins equals “heritability” of the survey scores. The authors attempt to address the obvious criticism that identical twins are likely to have a more shared environment than fraternal twins by citing studies that assert this is not so. Of course, if a weak study is published, all those that rely on it are weak as well. The problem with all of these studies is that they fail to separate the effects of genotype vs. phenotype. This is the major criticism of “twins reared apart” studies – similarities between identical twins reared apart aren’t automatically genetic, because they look the same (and often have similar mannerisms). Researchers seriously underestimate the importance of visual cues in affecting human interpersonal interactions. Hence, their social interactions will have a greater tendency to be similar even when they live in different environments.

In a similar vein, when the authors claim that a majority of political attitudes are genetic, do they honestly think this explains why black women are likely to be more liberal than white men? Clearly phenotype, which drives much life experience, is the important difference here, not genotype. The authors also do not address at all the fact that many peoples’ political attitudes change over time, sometimes in an extreme fashion. Yet they assert with a straight face that when children have opposing political beliefs from their parents, it must be due to a genetic mutation. They actually even calculate a heritability for party affiliation at 0.14. Yes, 14% of your choice of party apparently is from those alleles for “republican” and “democrat” you have tucked away.

Oddly, considering the tone of most of the paper, the authors do manage to point out correctly (even going into some depth on the topic) that all people are a product of the interaction of their genotype with their environment. They seem to do this to bolster their point that political attitudes must be partly genetic, but the discussion shows that clearly they think genes are as important as the social scientists they are criticizing think environment is. They go so far as to express regret that the current polarizing political environment will not change because of assortative mating – those with overlapping political views are more likely to reproduce together (true), and thus the “political genes” of their offspring will make them more likely to be polarized. Then they go on to speculate about the evolution of these genes and their effect on society, as if they actually know something about how evolution works, after reading a few papers.

Looks like all of the people with Ph.D.’s in genetics and evolution just wasted their time. They could have had a different career and still published papers on the topic.

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